The present invention relates to single lever faucet assemblies and, more specifically, to single lever faucet assemblies including a valve cartridge adapted for easy installation and removal therefrom.
Present designs for single lever faucets are generally characterized by a pivoting arrangement which controls the degree of alignment between the valve spool, ball or disc and the valve inlets in order to control flow rate and mixing level from the hot and cold water supplies. U.S. Pat. No. 4,226,260 to Schmidt discloses a single lever faucet which is characteristic of this type. While single lever faucets have enjoyed a considerable degree of popularity, present designs suffer several disadvantages. The control arrangement permits both temperature and flow rate to be controlled by pivotal movement of the control lever in any direction within the free range of operation of the lever. Single lever faucets incorporating this design inherently lack adequate operating definition of the temperature and volume controls. Thus, operation of most present single lever faucets of this type is somewhat confusing and often requires a person to "play" with the faucet control lever in order to determine the proper adjustment of the faucet to attain the temperature and flow rate which is desired.
The ability of the faucet control mechanism to provide uniform movement of temperature regulation at any flow rate is referred to as a square operating pattern. A further disadvantage of many single lever faucet designs resides in their inability to provide uniform movement of temperature regulation at any flow rate. The gimbal-type control mechanism disclosed in U.S. Pat. No. 4,226,260 to Schmidt provides a delta operating pattern which results in variable temperature regulation movement. Thus, for example, whereas the stem of a valve may travel one inch from extreme hot to extreme cold in a full volume setting. only one-fourth inch may be provided for the same regulation when flow is at a trickle. This makes "fine tuning" very difficult, since the travel of one-sixteenth inch would far overshoot the desired selection, resulting in repeated attempts at correction. A square pattern, on the other hand, permits the same degree of travel at trickle settings as it does at full volume. Another advantage of a square pattern activation is the ability to preselect temperature before turning water on. The advantage of this feature can be readily appreciated by anyone who has experienced searching for the desired temperature setting on a shower faucet. Thus, a single lever faucet providing a square operating pattern offers a distinct improvement over other single lever faucet designs which inherently cannot provide a square operating pattern.
Another disadvantage which is present in certain types of single lever faucets involves the design of the flow pattern through the valve mechanism. Thus, it is perceived that many single lever faucet designs require valve arrangements which either segment the flow pattern therethrough, require the flow pattern to execute relatively sharp turns, or present other undesirable flow restrictions. Any obstruction or restriction in the flow pattern increases friction and results in a significant pressure decrease between the faucet inlet and outlet, thus reducing the maximum outlet flow rate attainable at any given inlet pressure.
Yet another disadvantage characteristic of all known single lever faucet designs resides in their lack of reversibility. For example, in plumbing back-to-back conventional faucet installations through a common wall, the supply connections to one of the faucets must be criss-crossed in order to orient the hot and cold water supply connections properly to both faucet installations. However, if the faucet temperature control is able to be reversed in orientation, simple parallel piping connections may be employed. Thus, it would be a distinct advantage to provide a single lever faucet assembly which avoids the disadvantages associated with having to criss-cross the hot and cold water supply lines in situations similar to that described above.
Finally, single lever faucets inherently have a more complicated valve arrangement than double lever faucets. This presents problems principly when replacement of a portion of the valve mechanism becomes necessary for any reason. In order to simplify installation and removal of the valve mechanism for replacement or repair purposes, many single lever faucets now use valve cartridges which are designed for quick and simple attachment and removal from the main faucet assembly. An example of such a cartridge is disclosed in U.S. Pat. No. 4,226,260 to Schmidt, previously mentioned above. One disadvantage of this assembly is that it requires the gimbal-type activating mechanism and control lever stem to be replaced in order to replace the valve mechanism. Since it is highly unlikely that both the valve mechanism and activating mechanism would become defective or worn out at the same time, this arrangement requires unnecessary replacement of working parts and is for this reason a disadvantage.